Flap Placard Speed

[BLANDINO GO]

From: BLANDINO GO <blandi...@boeing.com>

Please help. I am trying to understand what Flap Placard Speed Means.
Please explain in layman's terms. Any website I can read?

What does this mean "Lockouts have occured when the flaps were extended
from the F25 to F30 position with the gear retracted and at placard
speeds"? Please explain in layman's term. You can email me at
g...@asme.org

[Moderator: I have combined this person's two posts into one message, as
they are obviously linked]

[Todd Pattist]

From: Todd Pattist <tpat...@DONTSPAMME.snet.net>

>Please help. I am trying to understand what Flap Placard Speed Means.
>Please explain in layman's terms.

In the aircraft context, a "placard" is a marking or small
sign visible to the pilot or crew advising of some important
aircraft limitation. A common limitation that relates to
flap operation is the maximum airspeed at which the flaps
may be extended. That airspeed is usually called Vfe
(Velocity - Flaps Extended) but may also be called "flap
placard speed."

Flaps are most often used at a relatively slow speed, during
landing . Fairly large loads would be applied to the flap
mechanism if the flaps were extended at high airspeed.
Since they are not needed at those speeds, and because
weight is at a premium, they are made just strong enough for
use in the speed range where they are needed. The "placard"
tells the pilot what that maximum speed is.

For most small aircraft there is a single flap placard
speed. Above that speed, the flaps must be fully retracted.
Below that speed they can be partially or fully extended.
It's also possible for there to be several limiting speeds
for different flap extension amounts.

>What does this mean "Lockouts have occured when the flaps were extended
>from the F25 to F30 position with the gear retracted and at placard
>speeds"? Please explain in layman's term. You can email me at

It's hard to say, without context, but I read this as saying
that when the pilot extended the flaps from 25 degrees down
to 30 degrees down, while flying right at (or possibly
below) the max permitted airspeed, with the landing gear
retracted, a "lockout" occurred, i.e., something that the
pilot wanted to move would not move. I suspect that the
thing that was locked out was the landing gear, but that's
just a guess. It might have been the flaps. It isn't even
clear whether the "lockout" was an intentional interlocking
mechanism, that malfunctioned or simply an aerodynamic or
mechanical overload preventing the desired motion.

Landing gear can also have a maximum extension airspeed, and
there can be an airspeed sensor interlock preventing the
gear from lowering above that speed limit. The quoted text
might be saying that such an interlock was preventing the
gear from coming down, even though the speed was below the
limit, possibly due to strange airflow patterns near the
sensor when the flaps were changing from F25 to F30.

Todd Pattist
(Remove DONTSPAMME from address to email reply.)